Virtual lug loader

ABSTRACT

A virtual lug loader includes a lug loader for loading workpieces in a flow direction into the spaced apart lugs on a lugged conveyor, wherein the workpieces are transversely oriented relative to the flow direction. The lug loader includes an array of pairs of endless conveyors for conveying the workpieces downstream, wherein each pair of endless conveyors in the array include first and second endless conveyors. The first and second endless conveyors are spaced laterally apart across the flow direction. Each are aligned substantially in the flow direction. The array forms a continuous upper surface in the flow direction for supporting the workpieces translating downstream in the flow direction. Each pair of endless conveyors in the array overlap adjacent pairs of endless conveyors in the array. At least one pair of endless conveyors in the array include independently actuable first and second drives independently driving their corresponding first and second endless conveyors.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication No. 60/899,871 filed Feb. 7, 2007 entitled Virtual LugLoader.

FIELD OF THE INVENTION

This invention relates to an apparatus for the singulation or allocationof lumber into lug spaces on a lugged transfer, or other lumberconveying device, and in particular relates to an apparatus capable ofcollecting, singulating, straightening, allocating and consistentlyspacing, rough sawn lumber or planed finished lumber, or sticks ofvarying widths, thickness and lengths into consecutive spaced-apartlugs, or allocated spacings onto a transfer, or lugged transfer, or to astick placing device, at high speeds.

BACKGROUND OF THE INVENTION

Conventional lug loaders or singulators (hereinafter collectivelyreferred to as either lug loaders or singulators) have been found to beinadequate at higher feed speeds. They are also limited in their abilityto both singulate and allocate lumber. When lumber is of varying widthsand varying in thickness, or bowed, as may be predominant in curvesawing mills, cupped or crooked, and/or skewed on the transfer, itbecomes increasingly difficult to handle the lumber at desirable higherspeeds.

An example of a conventional lug loader is that taught in U.S. Pat. No.3,923,142 which issued to Rysti on Dec. 2, 1975. In particular, what isbeing taught is singulating boards by use of supporting arms rotatingaround a closed loop, the orientation of the supporting arms controlledby curved deflectors. Pressing arms in opposed radial pairs, arerotatably mounted above the supporting arm to synchronously clamp aboard onto a supporting arm. Downstream flow of the mat of boards isarrested by a stop on each supporting arm. Rysti does not disclose amechanism for straightening lumber which is skewed on the infeedtransfer in the lug loader. Applicants are also aware of U.S. Pat. No.5,518,106, which issued to Allard on May 21, 1996. Allard disclosesusing fixed pick-up shoes mounted onto rotating discs for engaging andsupporting boards being singulated. Fixed shoes however, have thedisadvantage that they may mark the underside of the board as the boardis translated over the top of the disc and as the board is released. Ifa board is finished, for example destined for cabinet making or thelike, then any marks from the shoe or overhead clamp will reduce thevalue of the board. Allard also discloses a speed-up belt to pull theboard away from the fixed shoes at the top of the disc to prevent theboard from being flipped over as the board is released from the shoes.In some mills the boards have been marked for trimming and gradingbefore the lug loader. Thus if the board has been flipped over by thesingulator, as may occur in the case of the Allard device, the boardmust be flipped back by hand to read the mark. This can be difficult ina high speed application.

Many lug loaders in the prior art, particularly those operating atslower feed speeds, require that, in order to stop the delivery ofboards to the singulator, the board mat moving downstream into thesingulator device must be pushed back upstream by the stopping means,that is forced away from, for example, the fixed pick-up shoe andclamping device. Worse yet, in some prior art devices the board deliverymechanism must be brought to a complete stop. Both pushing the mat ofboards back upstream, and stopping the board delivery mechanism, can beimpractical at high speed.

In the prior art applicant is also aware of U.S. Pat. Nos. 5,921,376 and6,199,683 which issued to Michell et al for, respectively, a High SpeedRevolving Lug Loader With Retracting Heel and Hook and a High SpeedRevolving Board Singulator With Retracting Shoe and Variable DwellDuckers, both of which describe the mechanical manipulation of boards toload the boards into individual lug spaces in a lugged outfeed transfer.

Applicant is also aware of the following U.S. patent Nos. in the priorart relating to the present invention: U.S. Pat. Nos. 4,077,524;4,144,976; 4,330,055; 4,638,440; 4,869,360; 5,419,425; 5,662,203; and5,813,512.

SUMMARY OF THE INVENTION

The proposed invention is a transfer system. The transfer system makesuse of conveyors such as chains or belts to move lumber piecesdownstream while oriented traversely across the flow path. The lumberpieces enter the virtual lug loading system according to the presentinvention moving transversely. The lumber pieces may enter as a tightlyspaced sheet or mat of pieces with no gaps, or the lumber pieces may berandomly spaced and oriented.

Within the system a first grouping of transfers create consistent gapsbetween individual lumber pieces. The speed with which the lumber piecesare translated downstream is varied to create spaces between the lumberpieces. The first group of transfers may be driven individually organged together. In one embodiment individual transfers or pairs oftransfers are selectively and independently actuable to vary theirspeeds so that the gaps may be created, for example, by increasing thevelocity of successive transfers in the downstream direction.

The transfers in the second grouping of transfers are individuallydriven. They maintain the gapping, that is the spacing between lumberpieces, and allow a surge capacity. Being individually driven, thesetransfers also provide for skew correction should the lumber piecesarrive skewed or skew during a transition from one transfer to another.These transfers gap and straighten the pieces as required so that onepiece is positioned into each lug space on downstream lugged transferchains. Thus, individually driven belts within this second grouping oftransfers provide skew correction to correct the orientation of skewedlumber pieces on the infeed to the lugged transfer being loaded. Keepingthe lumber pieces straight, that is oriented traversely across the flowpath on the infeed, helps deal the lumber pieces into the lug spaces.

Dealing the boards directly into lug spaces without a mechanical lugloader simplifies the loading of the lug spaces in the lugged transferas compared to the prior art. It improves operator access, and reducesthe amount of mechanical components requiring maintenance.

In one aspect of the present invention, servo controlled decks singulatethe lumber pieces and position them directly into a lugged chain.

In summary the virtual lug loader according to one aspect of the presentinvention includes a lug loader for loading workpieces in a flowdirection into the spaced apart lugs on a lugged conveyor, wherein theworkpieces are transversely oriented relative to the flow direction. Thelug loader includes an array of pairs of endless conveyors for conveyingthe workpieces downstream, wherein each pair of endless conveyors in thearray include first and second endless conveyors. The first and secondendless conveyors are spaced laterally apart across the flow direction.Each are aligned substantially in the flow direction. The array forms acontinuous upper surface in the flow direction for supporting theworkpieces translating downstream in the flow direction. Each pair ofendless conveyors in the array overlap adjacent pairs of endlessconveyors in the array. At least one pair of endless conveyors in thearray include independently actuable first and second drivesindependently driving their corresponding first and second endlessconveyors.

When a skewed workpiece, that is one which is skewed from its transverseorientation, is translating on the first and second endless conveyors,the first or second drive corresponding to one of the pair of endlessconveyors advances the upstream-most end of the workpiece relative toits downstream-most end to correct the workpiece to an un-skewedposition oriented transversely to the flow direction.

The array may include an upstream gapping section and a downstream lugloading section. Advantageously, the first and second endless conveyors,that is the pair or pairs of conveyors which are independently actuableso as to correctly orient skewed workpieces, is or are found within thelug loading section. However, it is not intended as limiting the scopeof the present invention to have only gapping sections followed by skewcorrection sections. It is intended that in the present invention alsoto interleaf gapping sections with skew correction pairs. Further, skewcorrection could be done anywhere within the transfer system instead ofjust the lug loading section.

The pairs of endless conveyors in the gapping section may translate theworkpieces in the flow direction at increasing downstream velocitiesbetween an upstream end of the gapping section and a downstream end ofthe gapping section. The increasing downstream velocities may besuccessively increasing downstream velocities corresponding tosuccessive pairs of endless conveyors between the upstream anddownstream ends of the gapping section.

The number or proportion of endless conveyors either overall to thesystem, or within the lug loading section, which are the independentlyactuable pairs of endless conveyors may be for example, not intended tobe limiting, substantially half of the number of pairs of endlessconveyors.

The independently actuable pairs of endless conveyors each havecorresponding selectively actuable drives so that each of those pairs ofendless conveyors is asymmetrically actuable to drive one endlessconveyor ahead of another endless conveyor to correct skew of aworkpiece on any one of those endless conveyors.

The adjacent pairs of endless conveyors in the array may overlap atadjacent ends thereof by one endless conveyor of the adjacent pairsbeing inset laterally across the flow direction relative to acorresponding second endless conveyor of the adjacent pairs.

The present invention also is intended to include within its ambit amethod of virtual lug loading corresponding substantially to the use ofthe above described apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of the virtual lug loader according tothe present invention shown in an elongated view having component viewsin FIGS. 1A, 1B and 1C intended to be viewed side-by-side in sequence.

FIG. 2 is a plan view of the virtual lug loader of FIG. 1 shown in anelongated view having component views in FIGS. 2A, 2B and 2C intended tobe viewed side-by-side in sequence.

FIG. 3 is the lug loader of FIG. 2 showing, diagrammatically, sensorsand controls.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As seen in the accompanying figures wherein similar characters ofreference denote corresponding parts in each view, the Virtual LugLoader according to the present invention includes a gapping section 10immediately upstream, relative to a direction of flow A, of lug loadingsection 12. Workpieces 14 arrive in direction A so as to form a mat orblanket 16 of workpieces 14 on infeed transfer 18. Workpieces 14arriving at the upstream end of infeed transfer 18 may be fed from, forexample, a tilt hoist, a landing table, an unscrambler, or other woodhandling machinery.

Mat 16 is formed on infeed transfer 18 as the workpieces are slowed ontransfer belts 20. At the downstream end of infeed transfer 18,workpieces 14 are urged onto the upstream ends 22 a of a first pair ofbelts 22 for progressively faster translation of each workpiece 14 indirection A as the workpieces are transferred from the downstream end ofinfeed transfer 18 onto sequentially and progressively faster successivepairs of belts 22, 24, 26, 28, and 30 within gapping section 10. Gappingsection 10 may, alternatively, may be thought of as a lumber separationzone. Thus, a workpiece 14 having a velocity V₀ in direction A on infeedtransfer 18, will, once handed off to the first pair of belts 22, have adownstream velocity V₁, and then sequentially increasing velocities V₂,V₃, V₄, V₅ thereby sequentially increasing the separation betweenindividual work pieces 14 by reason of the progressive acceleration ofthe boards between pairs of belts.

Advantageously, the separation between individual workpieces 14 isincreased as the length of the gaps, distance g between adjacentworkpieces is increased for example to approximately one hundredtwenty-five percent of the length of each lug space, distance 1, betweenlugs 32 a of lugged outfeed chains 32. It is understood that, althoughfive pairs of belts 22-30 are illustrated, it is not intended to limitthe present invention to five pairs of belts in gapping section 10 asmore or fewer pairs of belts will suffice so long as sequentialworkpieces 14 are separated in direction A so that gap distance g is atleast equal to lug space distance 1.

The pairs of belts 22, 24, 26, 28 and 30 in gapping section 10 may eachbe driven by variable frequency drives or induction motors 34 along withassociated gear heads. In the illustrated example, not intended to belimiting, each of the five speed-up zones corresponding to the five beltpairs are approximately sixteen inches long so that the length in thedownstream direction of gapping section 10 is approximately six foot,eight inches.

In a preferred embodiment, lug loading section 12 is immediatelydownstream, and cooperates with, the downstream end of gapping section10 so that workpieces 14 are smoothly handed off from belts 30, beingthe downstream most pair of belts in gapping section 10, to the firstpair of control zone belts 36 located immediately downstream of theinterface B between gapping section 10 and lug loading section 12. Lugloading section 12 is a workpiece control zone wherein skew may becorrected such as the skew of a workpiece 14′ illustrated in dottedoutline on control zone belts 38. Skew correction is accomplished byeach belt in each pair of control zone belts 36, 38, 40, 42, 44, and 46being able and adapted to selectively operate at different speeds. Inorder to correct skew, for example a skew angle alpha (a) of a skewedworkpiece 14′ the two belts 38, and subsequent downstream belts as needbe, are driven at different speeds relative to one another as board 14′passes over the belts, so that the lagging end of the boar catches upwith the advanced end of the board until the board is correctlypositioned perpendicularly across the direction of flow A.

Apart from operating to correct the skew of workpieces translatingdownstream in direction A, the independently actuable control zone beltsin the belt pairs of lug loading section 12 also, in addition to thosebelts in gapping section 10, operate to selectively space the boardsapart and synchronize the boards with upcoming lugs 32 a as the luggedoutfeed chains 32 rotate in direction C. Thus the control zone belts aredriven by a motion controller (not shown) to accelerate or deceleratepairs of belts 36, 48, 40, 42, 44 and 46 to simultaneously accelerate ordecelerate both belts in individual pairs of belts so as to accelerateor decelerate a workpiece which has been corrected for a skew. This isdone to synchronize and match the placement of a particular workpieceinto, for example, the middle of a corresponding lug space as theworkpiece exits the downstream end of lug loading section 12. Thus asmay be seen, the acceleration or deceleration of the sequence ofworkpieces 14 being translated downstream over the sequential array ofpairs of belts 38, 40, 42, 44 and 46, are selectively motion controlledso as to place a workpiece 14 entering onto the upstream end of thelugged outfeed chains 32 preferably into for example the middle of acorresponding lug space or otherwise exiting off the downstream end ofbelts 46 just after a pair of lugs 32 a rotate to the vertical as chains32 rotate endlessly around sprockets 48.

In the illustrated embodiment, not intended to be limiting, lug loadingsection 12 has six control zone belt pairs maybe thought of as six beltmodules each approximately sixteen inches long in the downstreamdirection for a total downstream length of eight feet. In one preferredembodiment, the motors 50 which selectively individually drive each beltin each belt module, may be servo motors having corresponding gearheads.

It is understood that sensors 52 such as seen in FIG. 3 and known in theprior art, and as would be known to one skilled in the art, would beprovided to detect the position of individual boards and that theinformation from the sensors is processed by a digital processor 54cooperating with the sensors and that the digital processors alsocooperates with a programmable logic controller (PLC) 56 via network 58which in turn cooperates with the motors for selectively driving thebelts 22, 24, 26, 28 and 30 in gapping section 10 and belts 36, 38, 40,42, 44 and 46 in lug loading section 12.

In interpreting both the specification and the claims, all terms shouldbe interpreted in the broadest possible manner consistent with thecontext. In particular, the terms “comprises” and “comprising” should beinterpreted as referring to elements, components, or steps in anon-exclusive manner, indicating that the referenced elements,components, or steps maybe present, or utilized, or combined with otherelements, components, or steps that are not expressly referenced.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

What is claimed is:
 1. A lug loader for loading workpieces in a flowdirection into the spaced apart lugs on a lugged conveyor wherein theworkpieces are transversely oriented relative to the flow direction, thelug loader comprising: an array of pairs of endless conveyors whereineach pair of endless conveyors in said array include first and secondendless conveyors which are spaced laterally apart across said flowdirection and each are substantially aligned in said flow direction, andwherein said array forms a continuous upper surface in said flowdirection for supporting a workpiece translating downstream in said flowdirection, said each pair of endless conveyors in said array overlappingadjacent pairs of endless conveyors in said array in said flowdirection, wherein at least one of said each pair of endless conveyorsin said array include independently actuable first and second drivesindependently driving corresponding said first and second endlessconveyors respectively, wherein, when the workpiece is skewed from itstransverse orientation, said first or second drive corresponding to saidat least one of said each pair of endless conveyors advances theupstream-most end of the workpiece relative to its downstream-most endto correct the workpiece to an un-skewed position oriented transverselyto the flow direction.
 2. The device of claim 1 wherein said arrayincludes an upstream gapping section and a downstream lug loadingsection, wherein said at least one of said each pair of endlessconveyors is within said lug loading section.
 3. The device of claim 2wherein said pairs of endless conveyors in said gapping sectiontranslate the workpiece in said flow direction at increasing downstreamvelocities between an upstream end of said gapping section and adownstream end of said gapping section.
 4. The device of claim 3 whereinsaid increasing downstream velocities are successively increasingdownstream velocities corresponding to successive said pairs of endlessconveyors between said upstream and downstream ends of said gappingsection.
 5. The device of claim 3 wherein substantially half of all ofsaid each of said first and second endless conveyors of said pairs ofendless conveyors in said lug loading section have correspondingselectively actuable drives so that said each pair of endless conveyorsin said lug loading section is asymmetrically actuable to drive oneendless conveyor ahead of another endless conveyor in said each pair ofendless conveyors in said lug loading section to correct skew of aworkpiece on any one of those endless conveyors.
 6. The device of claim5 wherein said adjacent pairs of endless conveyors in said array overlapat adjacent ends thereof by one endless conveyor of said adjacent pairsbeing inset laterally across said flow direction relative to acorresponding second endless conveyor of said adjacent pairs.
 7. Amethod for loading workpieces in a flow direction into the spaced apartlugs on a lugged conveyor wherein the workpieces are transverselyoriented relative to the flow direction, and wherein the lug loaderincludes an array of pairs of endless conveyors wherein each pair ofendless conveyors in said array include first and second endlessconveyors which are spaced laterally apart across said flow directionand each are substantially aligned in said flow direction, and whereinsaid array forms a continuous upper surface in said flow direction forsupporting the workpieces translating downstream in said flow direction,said each pair of endless conveyors in said array overlapping adjacentpairs of endless conveyors in said array in said flow direction, andwherein at least one of said each pair of endless conveyors in saidarray include independently actuable first and second drivesindependently driving corresponding said first and second endlessconveyors respectively, the method comprising the steps of: a) creatinggaps between the workpieces by accelerating the workpieces as they aretranslated downstream on the array, and b) when one or more of theworkpieces are skewed from their transverse orientation, said first orsecond drives corresponding to said at least one of said each pair ofendless conveyors advances the upstream-most end of a skewed workpiecerelative to its downstream-most end to correct the skewed workpiece toan un-skewed position oriented transversely to the flow direction. 8.The method of claim 7 wherein said array includes an upstream gappingsection and a downstream lug loading section, wherein said at least oneof said each pair of endless conveyors is within said lug loadingsection.
 9. The method of claim 7 wherein said pairs of endlessconveyors in said gapping section translate the workpiece in said flowdirection at increasing downstream velocities between an upstream end ofsaid gapping section and a downstream end of said gapping section. 10.The method of claim 8 wherein said increasing downstream velocities aresuccessively increasing downstream velocities corresponding tosuccessive said pairs of endless conveyors between said upstream anddownstream ends of said gapping section.
 11. The method of claim 8wherein substantially half of all of said each of said first and secondendless conveyors of said pairs of endless conveyors in said lug loadingsection have corresponding selectively actuable drives so that said eachpair of endless conveyors in said lug loading section is asymmetricallyactuable to drive one endless conveyor ahead of another endless conveyorin said each pair of endless conveyors in said lug loading section tocorrect skew of a workpiece on any one of those endless conveyors. 12.The method of claim 11 wherein said adjacent pairs of endless conveyorsin said array overlap at adjacent ends thereof by one endless conveyorof said adjacent pairs being inset laterally across said flow directionrelative to a corresponding second endless conveyor of said adjacentpairs.